Linux RDMA and InfiniBand development
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From: Christoph Hellwig <hch@infradead.org>
To: "Christian König" <christian.koenig@amd.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	dri-devel@lists.freedesktop.org, kvm@vger.kernel.org,
	linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org,
	Sumit Semwal <sumit.semwal@linaro.org>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	Leon Romanovsky <leon@kernel.org>,
	linux-rdma@vger.kernel.org, Maor Gottlieb <maorg@nvidia.com>,
	Oded Gabbay <ogabbay@kernel.org>
Subject: Re: [PATCH v2 4/4] vfio/pci: Allow MMIO regions to be exported through dma-buf
Date: Wed, 7 Sep 2022 05:03:30 -0700	[thread overview]
Message-ID: <YxiIkh/yeWQkZ54x@infradead.org> (raw)
In-Reply-To: <b6b5d236-c089-7428-4cc9-a08fe4f6b4a3@amd.com>

On Tue, Sep 06, 2022 at 12:38:44PM +0200, Christian König wrote:
> The problem is once more that this is MMIO space, in other words register
> BARs which needs to be exported/imported.

Everything used for P2P is bar space.

> Adding struct pages for it generally sounds like the wrong approach here.
> You can't even access this with the CPU or would trigger potentially
> unwanted hardware actions.

How would an access from the CPU vs anther device make any difference?

> Would you mind if I start to tackle this problem?

Yes, I've been waiting forever for someone to tacke how the scatterlist
is abused in dma-buf..

  parent reply	other threads:[~2022-09-07 12:03 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-31 23:12 [PATCH v2 0/4] Allow MMIO regions to be exported through dma-buf Jason Gunthorpe
2022-08-31 23:12 ` [PATCH v2 1/4] dma-buf: Add dma_buf_try_get() Jason Gunthorpe
2022-09-01  7:55   ` Christian König
2022-09-06 16:44     ` Jason Gunthorpe
2022-09-06 17:52       ` Christian König
2022-08-31 23:12 ` [PATCH v2 2/4] vfio: Add vfio_device_get() Jason Gunthorpe
2022-08-31 23:12 ` [PATCH v2 3/4] vfio_pci: Do not open code pci_try_reset_function() Jason Gunthorpe
2022-08-31 23:12 ` [PATCH v2 4/4] vfio/pci: Allow MMIO regions to be exported through dma-buf Jason Gunthorpe
2022-09-06  9:51   ` Christoph Hellwig
2022-09-06 10:38     ` Christian König
2022-09-06 11:48       ` Jason Gunthorpe
2022-09-06 12:34         ` Oded Gabbay
2022-09-06 17:59           ` Jason Gunthorpe
2022-09-06 19:44             ` Oded Gabbay
2022-09-07 12:07               ` Christoph Hellwig
2022-09-07 12:05         ` Christoph Hellwig
2022-09-07 12:33           ` Jason Gunthorpe
2022-09-07 14:29             ` Christoph Hellwig
2022-09-07 14:46               ` Oded Gabbay
2022-09-07 15:23               ` Jason Gunthorpe
2022-09-07 15:32                 ` Christoph Hellwig
2022-09-07 16:12                   ` Jason Gunthorpe
2022-09-09 13:24                     ` Christoph Hellwig
2022-09-09 14:09                       ` Jason Gunthorpe
2022-09-07 16:31                 ` Robin Murphy
2022-09-07 16:47                   ` Jason Gunthorpe
2022-09-07 17:03               ` Dan Williams
2022-09-07 15:01             ` Robin Murphy
2022-09-07 12:03       ` Christoph Hellwig [this message]
2022-09-07 15:08         ` Christian König
2022-09-07 15:23           ` Christoph Hellwig

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